The present invention relates to conveyor apparatus, and more specifically to conveyor apparatus designed to provide for control in the application of driving forces to the conveyed articles, in response to overload conditions, with the drive means for the conveyor being maintained in an energized state.
While it is known in the conveyor art to employ apparatus capable of responding to overload conditions to provide for the interruption of the conveying process, the interruption of the conveying process is normally achieved by the disabling or de-energizing of the drive apparatus. The control apparatus necessary to achieve the de-energizing of the drive apparatus is normally quite sophisticated, and therefore relatively expensive. In addition, while the prior art type of conveyor apparatus may be satisfactory when relatively light articles are being conveyed, or short distances are involved, these are not satisfactory for use with the conveying of extremely heavy articles that must travel long distances.
One practical area wherein the problems as mentioned above are prevalent, is with regard to dairy processing plants, as will be explained more completely hereinafter. While the present invention will be described with reference to its application to the conveying problem encountered in dairy processing plants, this is being done for purposes of illustration and not by way of limitation.
Concerning specifically the dairy industry, processing plants will often employ a plurality of rather lengthy conveyor lines which feed a single palletizing station, wherein cases of the bottled dairy products are stacked on pallets for loading aboard trucks. With present day practices, the dairy product is packaged in either bottles or cardboard containers, and then disposed within rather sturdy cases which afford protection during transportation. These cases, which may contain six or more bottles or containers, are then moved to a stacking station, wherein they are stacked three to six cases high and are positioned on conveyor apparatus for movement to the palletizing station. In this regard, normally three or more filling stations will feed to a single palletizing station.
At the palletizing station, the stacks of filled cases are received and positioned on pallets for loading into trucks. The conveyor apparatus leading into the palletizing station will supply stacks of cases thereto in single file with three or more stacks being received at a time and being moved laterally onto the pallets. Once the first group of stacked cases is on the pallet, a second group is moved onto the palletizing apparatus and is moved laterally onto the pallets adjacent the first group. This operation is repeated until the pallet is filled.
As can be appreciated from the above discussion, the palletizing operation requires the intermittent supply of stacked cases, with only a relative short duration between the interruption of supply. However, for efficient operation, it can also be seen that an adequate supply of stacks of cases must be provided. To achieve this, the conveyor apparatus leading to the palletizing station will generally be loaded with stacked cases for a substantial distance along the length thereof.
To achieve the intermittent supply of stacked cases, various types of control apparatus are employed, which include some form of stop member which engages the forwardmost case on the conveyor to retard movement. This stop member is removed from the path of the conveyor, permitting the prescribed number of cases to move onto the palletizing apparatus, and is then repositioned to preclude further movement of the stacked cases past the outlet end of the conveyor. With this approach there exists a number of problems, as discussed immediately hereinafter.
Because of the short duration in the interruption of supply to the palletizing station; and in view of the extremely heavy weight of the stacks of cases, it is not practical to rely upon interruption of the supply of power to the drive means to effect the desired control of the supplying operation. Therefore with the conveyor apparatus presently in use, the drive means is operated continuously. Accordingly, when the stop is inserted in the conveyor path, the drive means, normally in the form of a pair of endless chains, will merely slip with regard to the underside of the lowermost cases in the various stacks.
In addition the above-mentioned interruption in the conveying process results in a chain reaction, in that the forwardmost stack will be brought to rest by engagement against the stop, with the remaining stacks being brought to rest by engagement with the stack immediately in front. As can be appreciated, the engagement of these rather heavy stacks produces a shock load which is applied to the individual cases, as well as to the stop member.
The prior art type of conveyor apparatus thus has a number of inherent disadvantages. First, the slippage of the chains past the cases produces wear both on the cases and on the upper surface of the chain. Secondly, the cases, the containers for the dairy products and the overall conveyor apparatus, including the stop means, are subjected to rather high shock loads which ultimately result in damage and wear thereto.
Subsequent to introduction of the present invention, the above-discussed problems were merely tolerated in that the cases and conveyor machinery were constructed of sufficient strength to withstand the adverse operating conditions. The present invention solves these problems inherent in the prior art in a unique manner by providing for the interruption of and the resumption in the application of driving forces to the conveyed articles, without de-energizing the driving apparatus. As will be apparent, this is achieved while minimizing the shock loads encountered, as well as the wear due to drive chain slippage.
More specifically, the present invention provides a conveyor arrangement which includes an elongate stationary frame having support surface means therealong adapted to support a stack of filled cases. A support arrangement for the drive means is provided in association with the frame, which includes mounting means providing for movement of the drive means support and the drive means relative to the stationary frame and the support surface means thereon. The aforementioned mounting means is designed to be responsive to the weight of the conveyed articles on individual sections of the conveyor apparatus, such that when the weight of conveyed articles on a particular section exceeds a predetermined amount, the drive means will be positioned at a level which permits the stacked cases to rest on the frame support surface, thereby effecting an interruption in driving engagement. When the weight of stacked cases on a particular section is less than a predetermined amount, the drive means supporting arrangement will move the drive means upwardly above the frame support surfaces to bring the drive means into driving engagement with the stack of cases and thereby resume the conveying operation. The present invention, as will be explained more completely hereinafter, is designed to achieve re-establishment of driving engagement in a progressive manner so that the stacks will move along the conveyor in spaced relation. In addition, the gradual re-establishment of driving engagement minimizes the shock load to the drive means and associated apparatus.